A magnetic domain acts as a basic unit that records data in a magnetic storage device, and a principle of the magnetic domain is: When an individual magnetic domain is not magnetized, differentiated small magnetization regions are generated in the individual magnetic domain to reduce magneto-static energy. In one of the small magnetization regions, magnetic moments of a large quantity of atoms are neatly arranged along one direction. However, magnetic moments in adjacent small magnetization regions point in different directions, and therefore are canceled by each other. Therefore, the magnetic domain shows no magnetism. However, when an external magnetic field is applied to the individual magnetic domain to magnetize the individual magnetic domain, and when a magnetic field strength of the external magnetic field is strong to a certain extent, magnetic moments in all the small magnetization regions in the individual magnetic domain are arranged in a direction the same as a direction of the external magnetic field. The individual magnetic domain shows magnetism, and has a magnetization direction the same as the direction of the external magnetic field. Moreover, after the external magnetic field is withdrawn, the magnetism of the individual magnetic domain does not disappear, and a value is recorded in the magnetic domain as the magnetization direction.
A specific working principle of a current magnetic storage device known to the public is: When data is written, an electrical signal is input into a read/write component and a magnetic field that is perpendicular to a direction of the magnetic domain wall is generated, to magnetize a magnetic domain corresponding to the read/write component, making magnetization direction in the magnetic domain perpendicular to the magnetic domain wall. Moreover, a remnant magnetic field having a direction the same as the magnetization direction is generated. That is, two opposite magnetization directions can be recorded in the magnetic domain, where one magnetization direction represents data “0”, and the other magnetization direction records data “1”. In this storage mode, only a magnetic field perpendicular to a direction of a magnetic domain wall can be recorded in a magnetic domain, and each magnetic domain can represent only two different values, which cannot implement multi-valued storage, and cannot satisfy an increasing demand on multi-valued data applications.